Defrosting evaporators in refrigeration systems



Nov. 13, 1956 5. J. SWEYNOR 2,770,104

DEFROSTING EVAPORATORS IN REFRIGERATION SYSTEMS Filed ankle 15, 1955 I INVENTOR. STANLEY J SWEYNOR DEFROSTING EVAPORATORS IN REFRIGERA- TION SYSTEMS Stanley J. Sweynor, Portland, Greg.

Application June 15, 1953, Serial No. 361,470

1 Claim. (Cl. 62-11755) This invention relates to defrosting evaporators in refrigeration systems, and is particularly related to the defrosting of evaporators for low temperature systems.

The primary object of the invention is to produce and accumulate uncondensed refrigerant or hot gases to be supplied to the evaporators of an evaporator type system for defrosting the same.

With the present system of defrosting these evaporators, insufficient hot gases are available for defrosting the evaporators periodically, therefore it is the object of my invention to produce and accumulate sufiicient hot gases to almost instantly defrost the said evaporators.

To carry out this object, I have provided a means of heating the gases other than by the heat generated by the compressor.

These and other incidental objects will be apparent in the drawings, specification and claim.

Referring to the drawings:

Figure 1 illustrates a conventional type low temperature evaporator refrigeration system.

Figure 2 illustrates a conventional system having my new and improved auxiliary hot gas producer and accumulator installed within the said system.

Figure 3 is an end sectional view of the accumulator unit, showing the arrangement of the hot gas coils for changing the liquid into a gas.

Referring more specifically to the drawings:

I am first going to describe the operation of a conventional refrigeration hot gas system and how it operates in the defrosting of the evaporators. This system is shown in Figure 1. I use the same system in Figure 2, except that I add my invention thereto consisting of an accumu lator in combination with a heating unit for heating the refrigerant, turning the liquid into a gas.

I will now describe the operation of the conventional system illustrated in Figure 1. The evaporator unit is indicated by numeral 1. A heat exchanger is indicated at 2. A compressor is indicated at 3. A condenser at 4, and a liquid refrigerant receiver at 5.

We will now take the system through a frosting cycle. The gases are compressed by the compressor 3, delivering the same through the line 6, through the check valve 7, line 8, into the condenser 4, condensing the said gases into a liquid by the condenser and delivering the said liquids into the receiver 5.

Pressure in the receiver delivers liquid refrigerant through the line 9, into the coil within the heat exchanger 2 to the expansion valve 11, where it is delivered into the line 12 to the coils 13, and from the coils by way of the line 14 into the heat exchanger in the form of a gas, back to the suction side 15 of the compressor by way of the line 16. The expansion valve is controlled by the thermostatic bulb 17 in the usual manner.

We will now defrost the evaporator 1 in the following manner: The time clock 18 opens the magnetic valve 19. When this is done the uncondensed or hot gas leaves the compressor 3 by way of the T 20, through the line 21,

2,770,104 Patented Nov. 13,

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through the manual shut 01f valve 22, magnetic valve 19,

line 23, through the T 24, into the line 12 to the coils.

gases will condense in the cooling coil 13, which in turn.

will return the liquid form to the compressor, which may cause injury to the compressor. proved system, suflicient hot gases are generated to supply hot gases indefinitely to the evaporators for defrosting.

I will now describe the operation of my new and improved defrosting system. With my new system the hot gases are compressed within the compressor 3, delivered through the line 25, into the coil 26 of an accumulator unit 27, from these coils into the line 28, line 29, into the condenser 4. From the condenser 4, into the liquid receiver 5, out into the line 31 into the coil 10 of the heat exchanger 2, out of the said coil into the line 31 to the expansion valve 11, into the line 12, coil 13 of the evaporator 1, out of the line 14 into the heat exchanger 2, out into the suction line 32 into the accumulator 27, out of the accumulator in the form of gas by way of the suction tube 33, into the line 34 and back to the suction side 15 of the compressor 3.

The refrigerant having been delivered into the heat exchanger 2 may be either returned as :a gas by the line 32 into the accumulator 27, or it may be a liquid or combination of both. If in the form of a liquid, it is turned into a gas within the accumulator 27 before it is sucked out through the suction tube 33 to the compressor, thereby making it impossible to injure the compressor by liquids. The refrigerant coming back to the accumulator 27 is quickly converted into a vapor by the heat radiated from the coils 26, as these coils are receiving hot gas from the compressor 3.

I will now describe the operation of my new and improved defrosting system in the defrosting part of the cycle. The time clock 18 opens the magnetic valve 34. This will permit the gases being delivered by the line 28 to enter the line 35, passing through the valve 34 into the coil 36 of the heater unit 37, out into the line 38, into the T 24, into the line 12, coils 13 of the evaporator 1, out of the line 14, into the heat exchanger 2, into the accumulator 27, out the suction tube 33 into the intake side 15 of the compressor 3.

The primary feature of my defrosting system residesin the providing of a heater unit 37 for heating the hot gases delivered from the compressor and also heating the gases to a higher heat after they have been delivered from the compressor, providing a sutficient amount of hot gas to quickly defrost the evaporators 1. The heater unit contains a liquid which is heated by any suitable heating element, such as the electric heating tube 37A.

The evaporators could be defrosted from the heat developed by the heater 37 independent of the compressor at any time the time clock 18 opens the valve for defrostmg purposes, which in turn will deliver the hot gas through the evaporator coil 13, heat exchanger 2, accumulator and back to the compressor, and thus start the compressor. This would be the case in the event that the temperature of the locker room dropped to where the compressor had stopped.

In the event the compressor was stopped and the time clock 18 opened the magnetic valve 34 to defrost the With my new and im-.

evaporator 1, this defrosting would not take place in the conventional type shown in Figure 1, but with my new and improved defrosting system hot gases would be immediately delivered into the evaporator from the heater unit 37. With my new and improved system, the check valve indicated by numeral 7 in Figure l is eliminated, due to the fact that no liquids can reach the compressor with my system after they are converted to gas within the accumulator 27 on the return from the evaporator.

The accumulator 27 always turns the refrigerant from a liquid so that no liquids can reach the compressor, therefore protection for the compressor is afforded, as well as plenty of hot gas from the heater 37 is supplied for defrosting the evaporator.

What is claimed is:

In a refrigeration system including a compressor for delivering hot compressed gas refrigerant, a condenser connected with said compressor to receive the gas refrigerant therefrom, an evaporator connected between said condenser and said compressor to receive condensed liquid refrigerant from said condenser and return gaseous refrigerant to said compressor, a by-pass connection directly between said compressor and said evaporator and bypassing said condenser to deliver gas refrigerant from said compressor to said evaporator to defrost said evaporator, an accumulator connected between the evaporator and compressor to receive refrigerant from the evaporator and convert it to gas, a coil in the bottom of said accumulator and connected between said compressor and condenser to heat said accumulator by the hot compressed gas delivered by said compressor to said condenser, and an electric heater unit in said by-pass connection for heating the gas to expedite the defrosting of said evaporator.

References Cited in the file of this patent UNITED STATES PATENTS 2,637,983 Malkofi May 12, 1953 2,645,101 La Porte July 14, 1953 2,698,522 La Porte Jan. 4, 1955 

